1. Field of the Invention
This invention relates to humidification apparatus.
2. State of the Prior Art
In a typical humidifier, a fan draws a stream of air through a mist of fine water droplets, so that the water droplets can become entrained in the air stream. With certain kinds of humidifiers, the droplet-laden air stream is discharged directly into a room or working space. An example of such a space humidifier is described in U.S. Pat. No. 2,163,474. With other kinds of humidifiers, the droplet-laden air stream is conducted via a duct system to an area where the atmosphere is to be humidified. An example of such a humidifier designed for use with a duct system is described in U.S. Pat. No. 4,174,362.
In the humidifier described in U.S. Pat. No. 4,174,362, a mist of fine water droplets is formed adjacent the periphery of a disc-shaped centrifugal water slinger, and a stream of air is drawn through the mist by a fan located downstream of the water slinger. The water droplets entrained in the air stream pass through the rotating blades of the fan in travelling to the atmosphere to be humidified.
It has been found that when water droplets entrained in an air stream come into contact with the rotating blades of a fan, the droplets tend to agglomerate into larger-size drops of water that are too large for efficient transportation by the air stream through downstream ducting. Also, high-speed impact of entrained water droplets on the fan blades tends to cause erosion and/or corrosion of the surfaces of the fan blades.
In humidifiers of the prior art, the bearings that enabled rotation of the fans and water slingers were typically exposed to the humidifying mist, so that significant accumulation of moisture in the bearings was generally unavoidable. Such moisture tended to limit the useful lifetime of the bearings. Furthermore, centrifuging of the grease in the bearings further limited the useful lifetime of the bearings in prior art humidifiers.